Cathode having a u-shaped support member



April 4, 1 967 INVENTOR. JOHN E. FIN N J. E. FINN 3,312,854

CATHODE HAVING A V-SHAPED SUPPORT MEMBER Filed July 51, 1964 United States Patent 3,312,854 CATHUDE HAVENG A U-SHAPED UPPORT MEMBER John Edward Finn, Plainview, N.Y., assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed July 31, 1964, Ser. No. 386,670 2 Claims. (Cl. 313-278) My invention relates to a cathode for an electric discharge tube, and in particular to a directly-heated cathode for a transmitting tube in which the cathode comprises a plurality of thin, parallel-connected wires.

In a copending application, Ser. No. 132,835, filed Aug. 21, 1961, now U.S. Patent 3,177,393, a cathode is disclosed and claimed which comprises a plurality of thin, parallel-connected wires wound around a pair of U-caps slideable on a frame. mounted by means of springs to a fixed support for providing proper tension in the cathode wires.

The present invention is an improvement in the cathode disclosed and claimed in that application. More particularly, it has been found that when the wires are heat cycled it is necessary to maintain tension on the frame as a result of the thermal elongation and contraction of the wires.

In accordance with the present invention, a pair of internal compression springs, mounted on the frame, are employed to provide the tension required in the cathode wires thereby simplifying the construction of the cathode.

The invention will be described with reference to the accompanying drawing in which:

FIG. 1 is a sectional view of an electric discharge tube employing a cathode according to the invention;

FIG. 2 is a longitudinal sectional view of the cathode; and

FIG. 3 is an elevational view of the cathode.

Referring to the drawing, a frame comprising two U- shaped members 1, 2 are coupled together by insulating sleeves 3, 4 in which the U-shaped members are slideable. Compression springs 5, 6 resiliently urge the U-shaped members outwardly from each other. Supported at opposite ends of the U-shaped members are caps 7, 8 which support a plurality of parallel-connected wires 9 constituting the cathode. Surrounding the cathode is a grid 10 The frame is resiliently supported by posts 11 and 12, and an anode 13. The electrodes are enclosed by an evacuated envelope 14.

The cathode wires are held under tension by springs 5 and 6.

While the invention has been described with reference to a particular example, other modifications thereof will be readily apparent to those skilled in the art without departing from the spirit and scope thereof as defined in the appended claims.

What is claimed is:

1. A directly-heated cathode for an electric discharge tube comprising a support, a pair of U-shaped metal members mounted in opposed spaced relation, tubular insulating members slideable over the arms of said U- shaped members for insulating said U-shaped members from each other, resilient means supported by each of said U-shaped members engaging said tubular insulating members resiliently urging said U-shaped members apart, a pair of metal caps each of which is secured to one of said U-shaped members, and a plurality of longitudinallyextending parallel-connected thin wires axially wound about said caps.

2. In an electrical discharge tube having a cathode and another electrode, said cathode comprising a pair of U-shaped metal members mounted in opposed space relation, a pair of tubular insulating members slideable over the arms of said U-shaped members, resilient means supported by each of said U-shaped members engaging said tubular insulating members resiliently urging said U-shaped members apart, a pair of metal caps each of which is secured to one of said U-shaped members, a plurality of longitudinally-extending parallel-connected thin wires axially wound about said metal caps, and means to rigidly support at least one end of said cathode within said tube.

References Cited by the Examiner UNITED STATES PATENTS Re. 15,278 l/1922 Langmuir 313-257 X 1,652,164 12/1927 Coyer 313257 X 2,020,025 11/1935 Gardner 313-278 X JOHN W. HUCKERT, Primary Examiner. A. J. JAMES, Assistant Examiner. 

1. A DIRECTLY-HEATED CATHODE FOR AN ELECTRIC DISCHARGE TUBE COMPRISING A SUPPORT, A PAIR OF U-SHAPED METAL MEMBERS MOUNTED IN OPPOSED SPACED RELATION, TUBULAR INSULATING MEMBERS SLIDEABLE OVER THE ARMS OF SAID USHAPED MEMBERS FOR INSULATING SAID U-SHAPED MEMBERS FROM EACH OTHER, RESILIENT MEANS SUPPORTED BY EACH OF SAID U-SHAPED MEMBERS ENGAGING SAID TUBULAR INSULATING MEMBERS RESILIENTLY URGING SAID U-SHAPED MEMBERS APART, A PAIR OF METAL CAPS EACH OF WHICH IS SECURED TO ONE OF SAID U-SHAPED MEMBERS, AND A PLURALITY OF LONGITUDINALLYEXTENDING PARALLEL-CONNECTED THIN WIRES AXIALLY WOUND ABOUT SAID CAPS. 